Securely stopped vehicle method and apparatus

ABSTRACT

The braking system of a vehicle is securely engaged in response to the operator of the vehicle causing the vehicle to stop. The vehicle being stopped is determined in response to several conditions including a predetermined time of stopping as well as suspensions settling time. The braking system remains securely engaged in the event of a moving vehicle colliding with the stopped vehicle. The braking system also remains securely engaged even if the foot of the operator is removed from the vehicle&#39;s brake pedal. The braking system is disengaged in response to the operator accelerating the vehicle, such as the operator&#39;s pressing of the vehicle&#39;s gas pedal, release of the vehicle&#39;s clutch and/or release of the vehicle&#39;s brake pedal. The rate of release of the braking system is responsive to the gas pedal position. The braking system is released rapidly in response to a substantially depressed gas pedal to facilitate a rapid start. The braking system is release gradually in response to a partially depressed gas pedal to facilitate a smooth start.

FIELD OF THE INVENTION

This invention relates in general to the field of vehicles and more particular to the field of vehicle braking systems.

BACKGROUND OF THE INVENTION

A vehicle, such as a street driven automobile, often stops at intersections in response to traffic lights. While waiting for a traffic light signal to indicate a time to accelerate, the vehicle is supposed to remain stopped. A problem arises when, contrary to the intention of a vehicle operator, the vehicle does not remain stopped. One example of a situation where a vehicle may undesirably accelerate from a stopped condition is when an operator's foot accidentally slips off of the vehicle's brake pedal. Another example is when a vehicle is impacted from the rear, the operator's foot may slip off the brake pedal or may not have enough brake pressure to prevent forward motion of the vehicle. Such situations can result in a collision with another vehicle. Since vehicle collisions are undesirable, it is desirable to provide a vehicle that remains securely stopped when the operator intends the vehicle to be stopped.

When the traffic light generates a green light signal, it is desirable to provide a securely stopping vehicle which accelerates in a way the operator is accustom: fast starts for rapid acceleration and smooth starts for normal acceleration. Furthermore, when operating the vehicle in slow traffic or approaching a stop light it is desirable that a vehicle with secure stopping does not interfere with low speed acceleration and braking of the vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a block diagram of a vehicle operating in accordance with the present invention.

FIG. 2 shows a basic flow diagram for a method of securing a motor vehicle in a stopped condition in accordance with the present invention.

FIG. 3 shows a detailed flow diagram of the step of determining if a vehicle has been stopped.

FIG. 4 shows a detailed flow diagram of the step of determining if a vehicle is to accelerate.

FIG. 5 shows a detailed flow diagram of the step of disengaging the secure stop mode.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a block diagram of a vehicle operating in accordance with the present invention. The vehicle has four wheels, 101-104, each wheel having a corresponding brake, 105-108. The brakes 105-108 may be either disk or drum or other system for stopping the vehicle. In a front wheel drive embodiment, the front wheels 101-102 are driven by an engine 110 and a transmission 112. The engine is preferably an internal combustion engine as is commonly used in vehicles today. The transmission is either an automatic transmission or a manually shifted transmission having a manually operated clutch for coupling the engine to the wheels. The engine is manually throttled by a throttle or gas pedal 120 and the clutch is manually controlled by a clutch pedal 122. A brake controller 130 is manually operated by a brake pedal 135. The brake controller may include a master cylinder or an anti-lock brake system for controlling the brakes 105-108. In operation, when a foot of the operator applies increasing pressure to the gas pedal, the speed of the vehicle increases. When the foot of the operator applies pressure to the brake pedal, the speed of the vehicle decreases. The amount of pressure applied to the brake pedal regulates the rate at which the speed of the vehicle decreases. When the vehicle has stopped, typically very little brake pressure is required to maintain the vehicle in a stopped condition. In a vehicle with an automatic transmission, the typical user applied brake pressure need only be enough to overcome the minimal acceleration of an idling engine which is applied to the wheels. In a vehicle with a manual transmission, the typical user applied brake pressure need only be enough to overcome accelerations due to the vehicle being situated on a hill.

With such little pressure required to typically maintain a vehicle in a stopped condition, an operator may unintentionally provide too little brake pressure, enabling the vehicle to move, which may result in a collision. Examples of unintentionally providing too little brake pressure include: when the operator is excessively tired or sleepy; when the operator is tending to other matters while the vehicle is stopped, such as caring for children, fetching documents, or operating a radio receiver, cassette tape or compact disk; or when the operator is actively engaged in conversations on a wireless phone or with fellow passengers or while singing a song.

Furthermore, with such little pressure required to typically maintain a vehicle in a stopped condition an operator is unlikely to be providing the significant brake pressure needed to prevent the vehicle from colliding with a third vehicle in the event of being impacted by a second moving vehicle. This is particularly true if the operator's vehicle is impacted from either from the rear or front by the second vehicle. Such collisions are typical when a vehicle is stopped at an intersection.

When acceleration from a stopped condition is desired, because a traffic light turns green for example, the foot of the operator of a vehicle with an automatic transmission is typically removed from the brake pedal and applied to the gas pedal. A small delay results from the time the light turns green and the foot is moved from the brake pedal to the gas pedal. The operator of a vehicle with a manual transmission typically has one foot an the clutch pedal and one foot on the brake pedal waiting for the traffic light to turn green. A triple movement is required when the light turns green, one foot is removed from the brake pedal and then applied to the gas pedal while the second foot releases the clutch pedal. This can be a complex operation, particularly when the vehicle is directed up a hill because the vehicle tends to unintentionally roll backwards between the time when the brake pedal is released, the gas pedal is pressed and the clutch pedal is released.

The invention provides for the problems with a secure stop controller 150 and a stop detector 155. The secure stop controller 150 receives signals from the gas pedal 120, clutch pedal 122, brake pedal 135 and stop detector 155 and applies an additional signal to brake controller 130 to apply or release brakes 105-108. The stop detector 155 is coupled to a velocity detector such as a speedometer. Alternately, the stop detector 155 may be used in conjunction with a slip detector, an anti-lock brake system or other vehicle component that is able to determine if the vehicle is stopped. In the preferred embodiment the stop detector 155 generates a vehicle stopped signal shortly after the vehicle has stopped.

FIG. 2 shows a basic flow diagram for a method of securing a motor vehicle in a stopped condition in accordance with the present invention. Refer also to FIG. 1. When step 160 determines that the vehicle has stopped, stop detector 155 generates a vehicle stopped signal. Most normal driving functions are performed during step 160, until the vehicle is stopped. In response, secure stopping is engaged at step at step 162 where the secure stop controller 150 sends a secure stop signal to the brake controller 130 to engage the brakes 105-108 with a force equivalent to significant brake pedal pressure. If the brake controller is an anti-lock brake system, the brake controller may modulate the brakes to provide improved stopping power in the event of a collision with the second moving vehicle. Since the vehicle is stopped, the operator is unaware of any significant braking force applied to brakes by the secure stop controller. Then step 164 determines if the operator intends for the vehicle to accelerate. In various embodiments this determination is made in response to the operator applying pressure to the gas pedal, releasing the clutch pedal or releasing the brake pedal, or a combination thereof. In response, step 166 disengages secure stopping. Secure stop controller 150 terminates the secure stop signal and the brake controller 130 disengages the brakes 105-108 allowing the speed of the vehicle to increase.

FIG. 3 shows a detailed flow diagram of the step of determining if a vehicle has been stopped. This corresponds to step 160 of FIG. 2. After entry at step 170, a timer is reset at step 172. The timer continues to be reset if vehicle velocity is not zero at step 174 and the brake pedal is not pressed at step 176. If however, the velocity is zero and while the brake pedal remains pressed for preferably two seconds at step 178, then the vehicle stopped signal is generated and the flow exits at step 180 to proceed to step 162 of FIG. 2. Thus, the vehicle is stopped for a predetermined time of two seconds with the brake applied before the secure stop signal is generated at step 162. Other predetermined times may be used. Alternately, the vehicle stopped signal could be generated when the velocity is zero for a different predetermined time. Or the vehicle stopped signal could be generated after the vehicle has stopped and the suspension settles out from the typical front end dive and consequential rocking motion resulting from the vehicle stopping. This settling could be sensed by a vehicle with active suspension or suspension motion sensors or accelerometers. This embodiment automatically compensations for aging suspension components such as shock absorbers that may increase the suspension settling time with age. These methods are an improvement over generating the vehicle stopped signal simply in response to the speed equaling zero because the secure stopping system is typically not engaged in stop and go traffic where a vehicle crawls along at a low speed with abrupt applications of the brake which may temporarily bring the vehicle to a stop. In such cases it may be desirable to not engage the secure stopping.

FIG. 4 shows a detailed flow diagram of the step of determining if a vehicle is to accelerate. This corresponds to step 164 of FIG. 2. After entry at step 190 step 192 checks if the clutch is released. This step is always “NO” for an automatic transmission. Step 194 checks if the gas pedal is pressed. This is an optional step for a manual transmission. This process effectively causes the system to remain in the secure stop mode until the operator either releases the clutch or presses on the gas pedal. Upon detection of either event, the process exits through step 192 to step 166 of FIG. 2 to disengage the secure stop mode. In the preferred embodiment, once the secure stop mode is engaged, the vehicle will remain stopped if the brake pedal pressure is reduced or even if the operator's foot is removed from the brake. This prevents unintentional movement of the vehicle. Furthermore if the vehicle is on a hill, it will not roll backwards. This simplifies the problem of accelerating from a stopped condition with a manual transmission while on a hill because the vehicle does not start to move as soon as the operator's foot is removed from the brake. In an alternate embodiment where the secure stop mode is released only in response to release of the clutch. In this embodiment the operator may even begin to rev the engine before the secure stop mode releases brakes in response to the operator releasing the clutch, thereby assuring that the engine is producing sufficient power to begin climbing the hill as the clutch is released. A further step may be added to ensure that the transmission is not in a neutral condition before disengaging the secure stop mode.

FIG. 5 shows a detailed flow diagram of the step of disengaging the secure stop mode. This corresponds to step 166 of FIG. 2. The flow enters at step 200. Step 202 checks if the throttle or gas pedal 120 is more than halfway depressed. This step corresponds to determining the magnitude of a desired acceleration signal. If true then step 204 causes the secure stop signal to terminate in such a way as to cause the brake controller 130 to rapidly disengage the brakes 105-108. In this embodiment, the operator substantially depresses the throttle indicating a desire for rapid acceleration. In response, the brakes are rapidly released. However, if the throttle is less than half depressed, it is presumed that the operator desires a smoother transition from a stopped vehicle to a moving vehicle and the brakes are gradually released. Step 208 releases the brakes by 20% of the maximum secure stop setting every one hundred milliseconds until the brakes are released at step 210. This process occurs so long as the operator's foot remains on the gas pedal at step 212. Assuming the secure stop mode provides a maximum engagement of the brakes, steps 202, 208, 210 and 212 gradually release the brakes of a predetermined time as the gas pedal is depressed. In the preferred embodiment, the brakes transition from fully engaged to fully disengaged over a one-half second interval. If at any time during that one-half second interval throttle is depressed to more than one half at step 202, the brakes are entirely disengaged at step 204, allowing for more rapid acceleration. FIG. 5 shows one example of a release of the brakes corresponding to an amount of desired acceleration. Predetermined values other than those shown in FIG. 5 are anticipated. Other variations are also anticipated including a more direct relationship between throttle position and release rate of the brakes wherein the rate may be non-linear. Alternately, the brakes could be released according to a predetermined process that is independent of the throttle position, including a simple rapid release of the brakes.

For the vehicle operator desiring rapid acceleration from a traffic light, steps 200-206 adds no delay over a vehicle that does not have a secure stop mode. Indeed the secure stop mode enables even more rapid starts by reducing the time from the appearance of a green light to when the vehicle is accelerated. This is because the operator's foot may rest upon the gas pedal waiting for the green light while the secure stop mode applies the brakes for the operator. This eliminates the delay encountered by requiring the operator's foot to move from the brake pedal to the gas pedal in response to the green light.

For the vehicle operator desiring a smooth transition from a vehicle stopped mode to a vehicle moving mode, the gradual release of the brakes by steps 200,202, 208 and 210 eliminate any sudden jerking acceleration experienced by a rapid release of the brakes. Furthermore, the process recovers from an accidental light punching of the gas pedal while waiting at a traffic light without necessarily having to reapply the brakes. If during the one half second gradual brake release process, the operator's foot is removed from the gas pedal as determined at step 212, then releasing of the brake of step 208 is discontinued until the velocity of the vehicle returns to zero at step 214. Alternately, brake pressure can be gradually increased to further facilitate stopping of the vehicle. Thereafter, the process returns to step 162 of FIG. 2 to enable the secure stop mode. Thus, a short tap on the gas pedal slightly releases the brakes allowing a slight movement of the vehicle. Since the brakes are still applied, albeit with less force, the vehicle slows to a stop and again returns to the secure stop mode. This allows the operator to “inch” the vehicle forward by lightly tapping on the gas pedal. In an alternate embodiment, this function may be eliminated by eliminating steps 212-216 and having step 210 proceed directly to step 202.

In an alternate embodiment, the determination an operator's desire for acceleration of step 164 could be made in response to the operator simply releasing the brake pedal. While this mode may not prevent the vehicle from moving when the operator's foot is removed from the brake, it does ensure that the vehicle's brakes are securely engaged even with a light brake pressure while the vehicle is stopped.

The invention has the advantage in that most all of the hardware of FIG. 1 exists in a modern automobile. Enhanced processes performed by the brake controller, 130, secure stop controller 150 and stop detector 155 may be implemented in software executed in either an automobile's anti-lock braking system and/or electronic system controller.

Thus, what has been provided is a vehicle that remains securely stopped when the operator intends the vehicle to be stopped. What also been provided is a vehicle able to accelerate from a stop in a manner intended by the operator, as well as an improved mode of rapid acceleration from a stop and an improved mode of inching forward while stopped. 

What is claimed is:
 1. A securely stopped motor vehicle comprising: a braking controller for engaging a vehicle brake for reducing vehicle speed in response to a braking input from an operator of the motor vehicle; and a secure stop controller coupled to said braking controller and a velocity detector for determining the vehicle speed for generating a vehicle stopped signal in response to the vehicle having no speed, wherein said secure stop controller generates a secure stop signal in response the vehicle stopped signal, and said braking controller further engages the vehicle brake in response to the secure stop signal, the motor vehicle further comprising: an acceleration controller for generating an acceleration signal causing the vehicle to accelerate in response to an acceleration input from the operator, wherein said secure stop controller is further coupled to said acceleration controller for terminating the secure stop signal in response to the acceleration signal, thereby disengaging the vehicle brake in response to the acceleration signal, whereby the secure stop signal is maintained if the braking input from the operator is terminated or if an external acceleration is applied to the vehicle, thereby maintaining activation of the vehicle brake in response to external acceleration caused by a collision from another vehicle, and further wherein the vehicle has a suspension system having a settling response in response to the vehicle being stopped, wherein the velocity detector generates the vehicle stopped signal after determining the vehicle has been stopped and after determining completion of the settling response.
 2. The motor vehicle according to claim 1 wherein the velocity detector generates the vehicle stopped signal after determining the vehicle has been stopped for a predetermined time greater than or equal to the settling time.
 3. A method of securing a motor vehicle in a stopped condition comprising the steps of: automatically engaging a braking system operated by an operator of the vehicle for securely stopping the vehicle in response to the vehicle being stopped by the operator; automatically disengaging the braking system in response to an acceleration signal from the operator to enable acceleration of the vehicle, wherein the vehicle has a brake control enabling the operator to apply a varying pressure applied to the braking system, thereby allowing the operator to control an amount of braking of the vehicle and wherein said step of automatically engaging the braking system automatically increases the pressure applied to the braking system beyond a pressure applied by the operator in response to the vehicle coming to a complete stop.
 4. The method according to claim 3 wherein the vehicle has an anti-lock brake system capable of actively controlling the braking system wherein said step of automatically engaging the braking system engages the anti-lock brake system whereby the anti-lock brake system remains engaged if the vehicle is accelerated by an input from other than the acceleration signal.
 5. The method according to claim 3 further comprising the step of determining that the vehicle has been stopped for a predetermined time, wherein said step of automatically engaging the braking system is further responsive to said step of determining and the braking system is engaged only after the predetermined time.
 6. The method according to claim 3 further comprising the step of determining a magnitude of the acceleration signal, wherein said step of automatically disengaging the braking system is responsive to said step of determining a magnitude of the acceleration signal and disengages the braking system at a rate responsive to the magnitude of the acceleration signal, thereby diminishing a sudden acceleration experience in response to reduced magnitude acceleration signal and increasing a sudden acceleration experience in response to an increased magnitude acceleration signal.
 7. The method according to claim 3 wherein said step of automatically disengaging the braking system gradually disengages the braking system during a disengagement time, said method further comprising the steps of; determining a termination of the acceleration signal during the disengagement time; and returning to said step of automatically engaging the braking system in response to said step of determining.
 8. The method according to claim 3 wherein the acceleration signal is generated in response to the operator releasing the brake control.
 9. A motor vehicle comprising: a braking controller for engaging a vehicle brake for reducing vehicle speed in response to a braking input from an operator of the motor vehicle and for enabling the operator to apply a varying pressure to the vehicle brake, thereby allowing the operator to control an amount of braking of the vehicle; and a secure stop controller coupled to said braking controller and a velocity detector for determining the vehicle speed and for generating a vehicle stopped signal in response to the vehicle having no speed, wherein said secure stop controller generates a secure stop signal in response the vehicle stopped signal, and said braking controller further engages the vehicle brake by increasing the pressure applied to the vehicle brake beyond a pressure applied by the operator in response to the secure stop signal.
 10. The motor vehicle according to claim 9 wherein the secure stop signal is maintained if an external acceleration is applied to the vehicle, thereby maintaining activation of the vehicle brake in response to external acceleration caused by a collision from another vehicle.
 11. The motor vehicle according to claim 9 wherein the velocity detector generates the vehicle stopped signal after determining the vehicle has been stopped for a predetermined time.
 12. The motor vehicle according to claim 11 wherein the vehicle has a suspension system having a settling time in response to the vehicle being stopped, wherein the predetermined time is equal to or greater than the settling time.
 13. The motor vehicle according to claim 9 wherein the vehicle has a suspension system having a settling response in response to the vehicle being stopped, wherein the velocity detector generates the vehicle stopped signal after determining the vehicle has been stopped and after completion of the settling response.
 14. The motor vehicle according to claim 9 further comprising: an acceleration controller for generating an acceleration signal causing the vehicle to accelerate in response to an acceleration input from the operator, wherein said secure stop controller is further coupled to said acceleration controller for terminating the secure stop signal in response to the acceleration signal, thereby disengaging the vehicle brake in response to the acceleration signal.
 15. The method according to claim 14 wherein the acceleration signal is generated in response to the operator terminating the braking input.
 16. The motor vehicle according to claim 9 further comprising: an acceleration controller for generating a variable magnitude acceleration signal causing the vehicle to accelerate at a variable rate in response to a variable acceleration input from the operator and for determining a magnitude of the acceleration signal, wherein said braking controller automatically disengages the vehicle brake at a rate responsive to the magnitude of the acceleration signal, thereby diminishing a sudden acceleration experience in response to reduced magnitude acceleration signal and increasing a sudden acceleration experience in response to an increased magnitude acceleration signal.
 17. The method according to claim 9 further comprising an acceleration controller for generating an acceleration signal causing the vehicle to accelerate in response to an acceleration input from the operator, wherein said braking controller gradually disengages the vehicle brake during a disengagement time and further engages the vehicle brake in response to a termination of the acceleration signal during the disengagement time.
 18. The motor vehicle according to claim 1 further wherein: said acceleration controller generates a variable magnitude acceleration signal causing the vehicle to accelerate at a variable rate in response to a variable acceleration input from the operator and for determining a magnitude of the acceleration signal, and said braking controller automatically disengages the vehicle brake at a rate responsive to the magnitude of the acceleration signal, thereby diminishing a sudden acceleration experience in response to reduced magnitude acceleration signal and increasing a sudden acceleration experience in response to an increased magnitude acceleration signal.
 19. The method according to claim 1 wherein said braking controller gradually disengages the vehicle brake during a disengagement time and further engages the vehicle brake in response to a termination of the acceleration signal during the disengagement time. 